The present invention relates to a seed planter attachment for a plow, and more particularly to a chisel plow for use in no-till plowing in which the planter is resiliently mounted to the rear of the plow shank and means are provided to insure a constant seed planting depth.
Certain sections of the country, due to the arid climate and lack of a stable top soil, are cultivated using no-till farming methods. According to this method, a frame having a plurality of chisel plows is drawn behind a tractor or the like. The chisels are relatively narrow implements which dig furrows into the ground without exposing an appreciable amount of topsoil. Such plows also include a fertilizer knife for laying a small amount of fertilizer in the furrows. Seeds are subsequently deposited by the use of seed planters mounted rigidly to the chisel plows or to the frame so as to drop seeds into the furrows created by the plows. Examples of two such devices are shown by the Prince, U.S. Pat. No. 2,539,592 and Bruner, U.S. Pat. No. 2,195,652.
The Bruner device is bolted directly to the plow shank on a heavy support arm. The support arm and an associated brace plate maintain the height of the seed planter in fixed relation to the lower end of the chisel plow. In the Prince device, the seed planter is rigidly attached to the plow shank by means of a U-shaped clamping bracket.
The principal disadvantage of both the Prince and Bruner devices is that the depth of the deposited seeds can vary depending upon the soil conditions encountered by the plow. Since the plow is relatively heavy, it will dig deeper into soft broken soil than into hard, rocky soil. Since the planter is fixedly attached to the plow it deposits seeds at a depth that is constant relative to the plow. Thus, seeds can be deposited at uneven depths. In no-till farming it is more desireable to have seeds planted at a constant depth regardless of soil conditions. Another disadvantage of the Bruner and Prince devices is that obstacles encountered by the plow, such as rocks, can damage the planter since it has no resilience in a vertical direction so as to slide over such obstacles. The planter is normally of a lighter construction than the heavier and more rugged plow shank, and is thus more susceptible to damage.
In other designs unrelated to no-till farming, such as shown in the Scarlett, U.S. Pat. No. 1,864,280 and Altgelt, U.S. Pat. No. 1,897,355, a plow shank and seeder combination is mounted resiliently to the frame, but the seeder is rigidly mounted with respect to the plow shank. Thus, although the combination can respond to variable soil conditions, and there is less likelihood of damage from ground obstacles, this seed planter suffers from the same disadvantages as those occasioned by the Prince and Bruner devices. That is, the seeds are planted at uneven depths. It is critical for no-till farming, however, that seed depth remain constant regardless of the soil depth of the plow shank.
In yet another type of design, shown for example in the Oehler U.S. Pat. No. 2,975,844, a seed planter shoe is resiliently attached to a frame. Also attached to the frame ahead of the shoe is a plow. The seed planter has a depth adjustment feature consisting of a press wheel which maintains the planter at a constant depth relative to the ground regardless of the depth of the furrow opened by the plow. While this type of device addresses some of the problems noted above, it is an integrated device consisting of complicated linkage mechanism between the seed planter, the press wheel and the frame. As such, it would not be convenient for use as an attachment for an existing chisel plow.